Compositions comprising carboxy component and processes for photolithography

ABSTRACT

New photoresist compositions are provided that are useful for immersion lithography. Preferred photoresist compositions of the invention comprise one or more block copolymers. Particularly preferred photoresists of the invention can exhibit reduced leaching of resist materials into an immersion fluid contacting the resist layer dining immersion lithography processing.

The present invention relates to new photoresist compositions that areparticularly useful in immersion lithography processes. Preferredphotoresist compositions of the invention comprise one or more withblock copolymers. Preferred block copolymers can be substantiallynon-mixable with a resin component of the resist. Particularly preferredphotoresists of the invention can exhibit reduced defects followingdevelopment with an aqueous alkaline solution.

Photoresists are photosensitive films used for transfer of an image to asubstrate. A coating layer of a photoresist is formed on a substrate andthe photoresist layer is then exposed through a photomask to a source ofactivating radiation. The photomask has areas that are opaque toactivating radiation and other areas that are transparent to activatingradiation. Exposure to activating radiation provides a photoinducedchemical transformation of the photoresist coating to thereby transferthe pattern of the photomask to the photoresist coated substrate.Following exposure, the photoresist is developed to provide a reliefimage that permits selective processing of a substrate. See U.S. PatentApplication Publication 2006/0246373.

The growth of the semiconductor industry is driven by Moore's law whichstates that the complexity of an IC device doubles on average every twoyears. This necessitates the need to lithographically transfer patternsand structures with ever decreasing feature size.

While currently available photoresists are suitable for manyapplications, current resists also can exhibit significant shortcomings,particularly in high performance applications such as formation ofhighly resolved sub-quarter micron and even sub-tenth micron features.

We now provide new photoresist compositions and processes. Photoresistcompositions comprise one or more block copolymers.

More particularly, preferred photoresists of the invention may comprise:

(i) one or more resins,

(ii) a photoactive component which may suitably comprise one or morephotoacid generator compounds, and

(iii) one or more block copolymers. Preferably, the one or more blockcopolymers are substantially non-mixable with the one or more resins.

Preferred block copolymers comprise at least two domains or blocks (1)and (2):

(1) developer-solublizing block that comprises developer solublemoieties such as photoacid-labile groups (e.g. photoacid-labile ester oracetal groups) or other developer solubilizing groups such as carboxy(—COOH), fluoroalcohols such as —C(OH)(CF₃)₂, or optionally substitutedsulfonamide;

(2) a hydrophilic block that comprises repeat units will hydrophilicgroups such as longer chain alkyl groups (e.g. optionally substitutedC₄₋₂₅alkyl) including branched alkyl groups (e.g. optionally substitutedbranched C₄₋₂₅alkyl) such as polymerized 2,3,3-trimethyl butylacrylate.

Preferred block copolymers may comprise additional blocks or domains inaddition to (1) and (2), i.e. the copolymers may be triblocks,tetrablocks or other higher order multi-block polymers. For at leastcertain applications, a dual-block polymer (total of 2 domains orblocks) will be suitable. Thus, references herein to block copolymersare inclusive of polymers that comprise 2, 3, 4 or more distinct blocksor domains. As should be understood, the term “block” polymer orcopolymer as referred to herein indicates a polymer that comprises oneor more section of a first chemical structure separated by one or moresections of a different chemical structure or composition.

The size or molecular weight of each block or domain of a blockcopolymer of a photoresist of the invention may vary rather widely. Forat least certain applications, each block of a copolymer may have a Mwof at least 50 or 100, more preferably at least about 200, 300, 400,500, 600, 700, 800, 900, 10000, 1100, 1200, 1300, 1400, 1500, 1600,1700, 1800, 1900 or 2000. Each block of a block copolymer may havediffering molecular weights, or approximately equal (e.g. within about1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20 or 25 percent) molecular weights.

Each block of a block copolymer can vary in composition. For example,suitable will be blocks that consist essentially of (e.g. at least 70,80, 90, 95 or 98 weight percent) of a single repeat unit. Also suitablewill be blocks that are alternating or random polymer units of 2, 3, 4,5 or more distinct polymerized monomers.

Block copolymers used in photoresists of the invention may contain avariety of moieties including e.g. fluorinated groups such asfluoroalkyl including fluoro(C₁₋₂₅alkyl) including perfluoro(C₁₋₂₅alkylsuch as F₃C— and F₃CF₂C—; fluoroalcohols such as fluoro(C₁₋₂₅alcohols)including (F₃C)₂C(OH)—; sulfonamides including fluorinated sulfonamides;extended alkyl groups e.g. C₄₋₂₀alkyl including branched alkyl such ast-butyl; and Si-substituted groups such as Si(C₁₋₂₀alkyl); hetero(N, Oor S)-substituted carbocyclic aryl units, particularly hetero(N, O orS)-substituted multi-ring carbocyclic aryl units such as hydroxynaphthylgroups. Block polymers that comprise polymerized acrylate groups(including acrylate groups that contain photoacid-labile and/orfluorinated moieties) also are preferred.

Particularly preferred photoresists of the invention can exhibit reduceddefects associated with a resist relief image formed from thephotoresist composition. In certain aspects, micro-bridging betweenlines of the formed resist relief image can be minimized or avoided.

As referred to herein, one or more block copolymers that aresubstantially non-mixable with the one or more photoresist resins can beany block polymer added to a photoresist that results in reduced defectsupon aqeuous alkaline development.

Suitable block co polymers (including substantially non-mixable blockcopolymers) for use in photoresists of the invention includecompositions that comprise silicon and/or fluorine substitution.

Preferred block copolymers (which can be substantially non-mixablematerials) for use in photoresists of the invention also may compriseoptionally substituted sulfonamide groups, including groups such asRS(═O)(X)NR′₂ where R is a non-hydrogen substituent, particularly —OH(to provide —SO₃H), optionally substituted C₁₋₂₀alkyl, and anelectron-withdrawing group such as halogen especially fluoro orhaloalkyl such as fluoralkyl e.g. F₃C—. In the formula RS(═O)(X)NR′₂, Xis a spacer (e.g. a chemical bond or a 1 to 8 carbon linkage), and eachR′ is independently a hydrogen or non-hydrogen substituent such asoptionally substituted C₁₋₂₀alkyl including a group as defined for Rabove. Such sulfonamide groups suitably may be present on an alkyllinkage (e.g. C₁₋₁₂alkyl), a polymerized acrylate group, or othermoiety.

It thus should be understood that references herein to “sulfonamide” areinclusive of where a sulfono (SO₂) moiety is directly linked (e.g. X informula RS(═O)(X)NR′₂ is chemical bond) to nitrogen as well as where asulfono (SO₂) moiety is spaced by 1, 2, 3 or more atoms (such as carbonatoms, e.g. X in formula RS(═O)(X)NR′₂ is (—CH₂—)₁₋₃) from the nitrogenof the sulfonamide group.

In certain aspects of the invention, preferred are photoresistcompositions that comprise materials that comprise sulfonamide group(s)where a sulfono (SO₂) moiety is spaced by 1, 2, 3 or more non-nitrogenatoms from the most adjacent nitrogen of the sulfonamide moiety.

Additional preferred block copolymers (which can be substantiallynon-mixable materials) for use in photoresists of the invention also maycomprise carboxy (—COOH) groups, such as may be present on alkyl groupse.g. —(CH2)_(n)COOH where n is suitably from 1 to 20, or polymerizedacid acrylate groups such as may be provided by polymerization ofacrylic acid or methacrylic acid or by a group(CH₃)_(n)(CH_(m)═CH₂)C(═O)O(CH₂)_(p)COOH where n is 0 or 1, m is 2 or 3,p is an integer of from 1 to 12.

Still further preferred block copolymers (which can be substantiallynon-mixable materials) for use in photoresists of the invention also maycomprise hetero-substituted carbocyclic aryl units, particularlycarbocyclic aryl units substituted by oxygen or sulfur-containingmoieties such as hydroxyl, e.g. multi-ring substituted carbocyclic arylunits such as hydroxyl naphthyl.

Also preferred are those block copolymers (including substantiallynon-mixable block copolymers) that comprise photoacid-labile groups,such as photoacid-labile ester or acetal groups, including such groupsas described herein employed in a resin component of a chemicallyamplified photoresist.

Preferred substantially non-mixable block polymers for use inphotoresists of the invention also will be soluble in the same organicsolvent(s) used to formulate the photoresist composition.

Particularly preferred block copolymers (including substantiallynon-mixable block copolymer) for use in photoresists of the inventionalso will have lower surface energy and/or smaller hydrodynamic volumethan the one or more resins of the photoresist's resin component, or atleast one or more distinct blocks of the polymer will have such a lowersurface energy and/or smaller hydrodynamic volume than the one or moreresins of the photoresist's resin component. The lower surface energycan facilitate segregation or migration of the block copolymer to top orupper portions of an applied photoresist coating layer. Additionally,relative smaller higher hydrodynamic volume also can be preferredbecause it can facilitate efficient migration (higher diffusioncoefficient) of the block polymers to upper regions of the appliedphotoresist coating layer.

Preferred block polymers for use in photoresists of the invention alsowill be soluble in photoresist developer compositions (e.g. 0.26Naqueous alkaline solution such as 0.26N tetramethyl ammonium hydroxideaqueous developer). Thus, in addition to photoacid-labile groups asdiscussed above, other aqueous base-solubilizing groups may be includedin the substantially non-mixable materials such as hydroxyl,fluciroalcohol (e.g. —CH(CF₃)₂), carboxy and the like.

Suitable block copolymers for use in photoresists of the invention alsomay be in the form of particles. Such particles may include blockpolymers that are polymerized in the form discrete particles, i.e. asseparate and distinct polymer particles. Such polymer particlestypically have one or more different characteristics from linear orladder polymers such as linear or ladder silicon polymers. For example,such polymer particles may have a defined size and a low molecularweight distribution. More particularly, in a preferred aspect, aplurality of the polymer particles may be employed, in a photoresist ofthe invention with a mean particle size (dimension) of from about 5 to3000 angstroms, more preferably from about 5 to 2000 angstroms, stillmore preferably from about 5 to about 1000 angstroms, yet morepreferably from about 10 to about 500 angstroms, even more preferablyfrom 10 to 50 or 200 angstroms. For many applications, particularlypreferred particles have a mean particle size of less than about 200 or100 angstroms.

Additional suitable block copolymers may have Si content, includingsilsesquioxane materials, materials with SiO₂ groups, and the like.

Preferred imaging wavelengths of lithographic systems of the inventioninclude sub-300 nm wavelengths e.g. 248 nm, and sub-200 nm wavelengthse.g. 193 nm. In addition to one or more block copolymers, particularlypreferred photoresists of the invention may contain a photoactivecomponent (e.g. one or more photoacid generator compounds) and one ormore resins (which resins are distinct from the one or more blockcopolymers) that are suitably chosen from among:

1) a phenolic resin that contains acid-labile groups that can provide achemically amplified positive resist particularly suitable for imagingat 248 nm. Particularly preferred resins of this class include: i)polymers that contain polymerized units of a vinyl phenol and an alkylacrylate, where the polymerized alkyl acrylate units can undergo adeblocking reaction in the presence of photoacid. Exemplary alkylacrylates that can undergo a photoacid-induced deblocking reactioninclude e.g. t-butyl acrylate, t-butyl methacrylate, methyladamantylacrylate, methyl adamantyl methacrylate, and other non-cyclic alkyl andalicyclic acrylates that can undergo a photoacid-induced reaction, suchas polymers in U.S. Pat. Nos. 6,042,997 and 5,492,793, incorporatedherein by reference; ii) polymers that contain polymerized units of avinyl phenol, an optionally substituted vinyl phenyl (e.g. styrene) thatdoes not contain a hydroxy or carboxy ring substituent, and an alkylacrylate such as those deblocking groups described with polymers i)above, such as polymers described in U.S. Pat. No. 6,042,997,incorporated herein by reference; and iii) polymers that contain repeatunits that comprise an acetal or ketal moiety that will react withphotoacid, and optionally aromatic repeat units such as phenyl orphenolic groups; such polymers have been described in U.S. Pat. Nos.5,929,176 and 6,090,526, incorporated herein by reference, as well asblends of i) and/or and/or iii); 2) phenolic resins that do not containacid-labile groups such as poly(vinylphenol) and novolak resins that maybe employed in I-line and G-line photoresists together with adiazonaphthoquinone photoactive compound and have been described e.g. inU.S. Pat. Nos. 4,983,492; 5,130,410; 5,216,111; and 5529880;

3) a resin that is substantially or completely free of phenyl or otheraromatic groups that can provide a chemically amplified positive resistparticularly suitable for imaging at sub-200 nm wavelengths such as 193nm. Particularly preferred resins of this class include: i) polymersthat contain polymerized units of a non-aromatic cyclic olefin(endocyclic double bond) such as an optionally substituted norbornene,such as polymers described in U.S. Pat. Nos. 5,843,624, and 6,048,664,incorporated herein by reference; ii) polymers that contain alkylacrylate units such as e.g. t-butyl acrylate, t-butyl methacrylate,methyladamantyl acrylate, methyl adamantyl methacrylate, and othernon-cyclic alkyl and alicyclic acrylates; such polymers have beendescribed in U.S. Pat. No. 6,057,083; European Published ApplicationsEP01008913A1 and EP00930542A1; and U.S. patent application Ser. No.09/143,462, all incorporated herein by reference, and polymers thatcontain polymerized anhydride units, particularly polymerized maleicanhydride and/or itaconic anhydride units, such as disclosed in EuropeanPublished Application EP01008913A1 and U.S. Pat. No. 6,048,662, bothincorporated herein by reference, as well as blends of i) and/or ii)and/or iii);

4) a resin that contains repeat units that contain a hetero atom,particularly oxygen and/or sulfur (but other than an anhydride, i.e. theunit does not contain a keto ring atom), and preferable aresubstantially or completely free of any aromatic units. Preferably, theheteroalicyclic unit is fused to the resin backbone, and furtherpreferred is where the resin comprises a fused carbon alicyclic unitsuch as provided by polymerization of a norborene group and/or ananhydride unit such as provided by polymerization of a maleic anhydrideor itaconic anhydride. Such resins are disclosed in PCT/US01/14914 andU.S. application Ser. No. 09/567,634.

5) resins that contain Si-substitution including poly(silsequioxanes)and the like and may be used with an undercoated layer. Such resins aredisclosed e.g. in U.S. Pat. No. 6,803,171.

6) a resin that contains fluorine substitution (fluoropolymer), e.g. asmay be provided by polymerization of tetrafluoroethylene, a fluorinatedaromatic group such as fluoro-styrene compound, compounds that comprisea hexafluoroalcohol moiety, and the like. Examples of such resins aredisclosed e.g. in PCT/US99/21912.

Preferred photoresists of the invention include bothchemically-amplified positive-acting and negative-acting photoresists.Typically preferred chemically-amplified positive resists include one ormore resins that comprise photoacid-labile groups such asphotoacid-labile ester or acetal groups.

The invention further provides methods for forming a photoresist reliefimage and producing an electronic device using photoresists of theinvention. The invention also provides novel articles of manufacturecomprising substrates coated with a photoresist composition of theinvention.

Other aspects of the invention are disclosed infra.

As discussed above, particularly preferred photoresists of the inventioncan exhibit reduced defects following aqueous alkaline development. Suchdefects can include reduced organic residues in areas bared ofphotoresist upon development as well as reduced microbridging betweenimages resist lines or other features.

As discussed above, suitable block copolymers of photoresists of theinvention that substantially non-mixable (as referred to herein) withthe resist resin component can be readily identified by simple testing.In particular, as referred to herein, preferred substantiallynon-mixable block copolymers will provide a decreased occurrence oramount of defects upon aqueous alkaline development relative to acomparable photoresist relative to the same photoresist system that isprocessed into the same manner, but in the absence of the candidatesubstantially non-mixable material(s). Assessment of defects (or absencethereof) can be made via scanning electron micrography. Detection ofphotoresist material in the immersion fluid can be conducted asdescribed in Example 2 of U.S. Patent Publication 2006/0246373 andincludes mass spectroscopy analysis of the immersion fluid before andafter exposure to the photoresist. In such analysis, the immersion fluiddirectly contacts the tested photoresist composition layer for about 60seconds during exposure. Preferably, addition of one or more blockcopolymers provides at least a 10 percent reduction in photoresistmaterial (again, acid or organics as detected by mass spectroscopy)residing in the immersion fluid relative to the same photoresist thatdoes not employ such block polymer(s), more preferably the one or moreblock polymer(s) provide at least a 20, 50, or 100, 200, 500, or 1000percent reduction photoresist material (again, acid and/or organics)residing in to the immersion fluid relative to the same photoresist thatdoes not contain the candidate block polymer(s).

Preferred photoresists of the invention will result in less than 1.6 XE-10 (mole/cm²/sec) of photoacid generator material being leached intodeionized water or other overcoating immersion fluid for 60 secondsduring exposure by the analysis method described in Example 2 of U.S.Patent Publication 2006/0246373.

Preferred photoresists of the invention may have preferred water contactangles. As referred to herein, water contact angles, such as static,receding, advancing sliding, developer static can be determined inaccordance with the producers disclosed in Burnett et al., J. Vac. Sci.Techn. B, 23(6), pages 2721-2727 (November/December 2005). Preferredphotoresists (as determined as a spin-coated layer with solvent removedby soft-bake) will have a receding angle of at least 65°, morepreferably at least 70°. Additionally, preferred substantiallynon-mixable materials (as determined as a spin-coated layer with solventremoved by soft-bake) will have a receding angle of at least 65°, morepreferably at least 70°.

As discussed above, suitable block copolymers for use in polymers of theinvention may comprise a variety of moieties functionalities. Forinstance, block copolymers may comprise non-aromatic units such asprovided by polymerization of an acrylate or an optionally substitutedcyclic olefin (particularly carbon alicyclic or heteroalicyclic group)such as a polymerized optionally substituted norbornene. Suitably, atleast one of the resin repeat units contains a photoacid-labile moietysuch as a photoacid-labile ester or acetal moiety. For use in aphotoresist imaged at 193 nm, particularly preferred block polymers aresubstantially free of any aromatic moieties other than the hydroxynaphthyl groups or other hetero-substituted carbocyclic aryl groups.

Additional preferred polymer units may be provided by polymerization ofan anhydride such as maleic anhydride or itaconic anhydride; or lactonessuch as provided by polymerization of a suitable acrylate e.g.acryloxy-norbornane-butyrolactone and the like.

Preferred substituted hetero-substituted carbocyclic aryl units forincorporation into a block copolymer are naphthyl groups as well asother substituted carbocyclic aryl moieties such as hetero-substitutedphenyl, anthracenyl, acenaphthyl, phenanthryl, and the like. Generally,hetero-substituted carbocyclic aryl groups having multiple fused rings(e.g. 2 or 3 fused rings, at least one of which is a carbocyclic aryl)are preferred such as hetero-substituted naphthyl, anthracenyl,acenaphthyl, phenanthryl, and the like.

A carbocyclic group may have a variety of hetero-substituents, withoxygen- and sulfur-containing substituents being generally preferred.For instance, preferred hetero-substituted carbocyclic aryl groups ofresins of the invention include those aryl groups having one or morehydroxy (—OH), thio (—SH), alcohol (e.g. hydroxyC₁₋₆alkyl), thioalkyl(e.g. HSC₁₋₆alkyl), alkanoyl (e.g. C₁₋₆alkanoyl such as formyl or acyl),alkylsulfide such as C₁₋₆alkylsulfide, carboxylate (includingC₁₋₁₂ester), alkyl ether including C₁₋₈ether, and the like. Preferably,at least one hetero atom of the hetero-containing substituent has ahydrogen substituent (e.g. hydroxy is preferred over alkoxy). It is alsopreferred that the hetero group has the hetero atom directly linked tothe carbocyclic ring (such as a hydroxy or thio ring substituents), or ahetero atom is a substituent of an activated carbon such as a ringsubstituent of —CH₂OH or —CH₂SH, or other primary hydroxy or thio alkyl.

Preferred substituted carbocyclic aryl units for incorporation into ablock polymer are naphthyl groups substituted with one or more hydroxy(—OH), thio (—SH), alcohol (e.g. hydroxyC₁₋₆alkyl), thioalkyl (e.g.HSC₁₋₆alkyl), alkanoyl (e.g. C₁₋₆alkanoyl such as formyl or acyl),alkylsulfide such as C₁₋₆alkylsulfide, carboxylate (includingC₁₋₁₂ester), alkyl ether including C₁₋₈ether, and the like. Preferably,at least one hetero atom of the hetero-containing substituent has ahydrogen substituent (e.g. hydroxy is preferred over alkoxy). It is alsopreferred that the hetero group has the hetero atom directly linked tothe carbocyclic ring (such as a hydroxy or thio ring substituents), or ahetero atom is a substituent of an activated carbon such as a ringsubstituent of —CH₂OH or —CH₂SH, or other primary hydroxy or thio alkyl.A hydroxynapthyl group such as provided by polymerization of vinylhydroxyl naphthyl is a preferred unit of a block copolymer for use in aphotoresist of the invention.

A block copolymer may suitably contain a relatively wide range ofamounts of hydroxy naphthyl units or other hetero-substitutedcarbocyclic aryl groups. Suitably, a block copolymer may contain quiteminor amounts of the hydroxy naphthyl units. For example, a blockcopolymer may suitably contain less than about 50 or 40 mole percent ofhetero-substituted carbocyclic aryl units based on total units of aresin, or even less than about 30, 20, 15 or 10 mole percent ofhetero-substituted carbocyclic aryl units based on total units of theblock polymer. Indeed, a block polymer may suitably contain about 0.5,1, 2, 3, 4, 5, 6, 7 or 8 mole percent of hydroxy naphthyl units based ontotal units of the resin. Typically, a block copolymer will contain atleast about 1, 2, 3, 4 or 5 mole percent of hetero-substitutedcarbocyclic aryl units such as hydroxy naphthyl units based on totalresin units, if the block copolymer contains such units. Generallypreferred are block copolymers that contain at least or up to about 5,10, 20, 30, 40, or 45 hetero-substituted carbocyclic aryl units such ashydroxy naphthyl units based on total resin units.

Block copolymer are preferably employed in photoresists imaged at 193 nmand suitably will be substantially free of any phenyl or other aromaticgroups other than the hetero-substituted carbocyclic aryl units. Forexample, preferred block copolymers contain less than about 5 molepercent aromatic groups other than the hetero-substituted carbocyclicaryl units, more preferably less than about 1 or 2 mole percent aromaticgroups hetero-substituted carbocyclic aryl units.

As discussed, various moieties of block copolymers and other materialsmay be optionally substituted. A “substituted” substituent may besubstituted at one or more available positions, typically 1, 2, or 3positions by one or more suitable groups such as e.g. halogen(particularly F, Cl or Br); cyano; C₁₋₈ alkyl; C₁₋₈ alkoxy; C₁₋₈alkylthio; C₁₋₈ alkylsulfonyl; C₂₋₈ alkenyl; C₂₋₈ alkynyl; hydroxyl;nitro; carbocyclic aryl such as phenyl, napthyl, acenaphthyl,anthracenyl; alkanoyl such as a C₁₋₆ alkanoyl e.g. acyl and the like;etc.

Block copolymers for use in photoresists of the invention may beprepared by known procedures including a free radical polymerizationprocess such as disclosed in U.S. Pat. Nos. 6,515,088 and 6,379,874. Apreferred synthesis is also set forth in the examples which follow.Preferred initiators include 1-octylperoxy-9-borafluoene and can promoteso-called “living” free radical polymerization.

Preferably a block copolymer will have a weight average molecular weight(Mw) of about 800 or 1,000 to about 100,000, more preferably about 2,000to about 30,000, still more preferably from about 2,000 to 15,000 or20,000, with a molecular weight distribution (Mw/Mn) of about 3 or less,more preferably a molecular weight distribution of about 2 or less.Molecular weights (either Mw or Mn) of the resins of the invention aresuitably determined by gel permeation chromatography.

It is also preferred that the molar ratio of (1) developer affinityblock(s) to (2) hydrophobic block(s) of a particular block copolymer beapproximately equal, e.g. with a relative range of 65:35, morepreferably 60:40, more preferably 55:45 or even more preferably about50:50. Such relative ranges can avoid undesired micelle formation.

Specifically preferred block copolymers for use in photoresists of theinvention include the following:

As discussed above, suitable block copolymers may include Si-containingmaterials. Suitable block copolymers include nanostructuredcompositions, which are commercially available from groups such asHybrid Plastics (Fountain Valley, Calif.), Sigma/Aldrich, and others.Such materials may include molecular silicas which have a Si—O coreenveloped by organic groups; silanols; and polymers and resins whichinclude silsesquioxane cage-structured compounds and may be silicones,styrenics, acrylics, alicyclics such as norbornenes and others.

Particles (including organic particles) useful as block copolymersinclude Si-containing and fluorinated materials. Such particles arecommercially available, or can be readily synthesized, e.g. by reactionof one or more monomers together with a crosslinking agent and aninitiator compound If desired. The reacted monomers may havesubstitution as desired e.g. fluorine, Si groups, photoacid-labilegroups such as photoacid-labile esters or acetals, otherbase-solubilizing groups such as alcohols and the like. See Example 1 ofU.S. Patent Application Publication 2006/0246373 for an exemplarysynthesis of such particles produced with multiple distinct monomers,where one of the monomers provides a photoacid-labile group to theresulting polymer particle.

The block copolymer(s) may be present in a photoresist composition inrelatively small amounts and still provide effective results. Forinstance, the one or more block polymers may be suitably present inabout 0.1 to 20 weight percent based on total weight of a fluidphotoresist composition. Suitable amounts also are provided in theexamples which follow.

In certain aspects of the invention, excluded are photoresists thatcontain a fluorinated surfactant material where the surfactant materialcontains from 30 to 60 mass % of fluorine atoms, or even 20 mass %fluorine atoms, or up to 70 mass percent fluorine atoms.

As discussed above, preferred photoresists for use in accordance withthe invention include positive-acting or negative-acting chemicallyamplified photoresists, i.e. negative-acting resist compositions whichundergo a photoacid-promoted crosslinking reaction to render exposedregions of a coating layer of the resist less developer soluble thanunexposed regions, and positive-acting resist compositions which undergoa photoacid-promoted deprotection reaction of acid labile groups of oneor more composition components to render exposed regions of a coatinglayer of the resist more soluble in an aqueous developer than unexposedregions. Ester groups that contain a tertiary non-cyclic alkyl carbon(e.g. t-butyl) or a tertiary alicyclic carbon (e.g. methyladamantyl)covalently linked to the carboxyl oxygen of the ester are oftenpreferred photoacid-labile groups of resins employed in photoresists ofthe invention. Acetal photoacid-labile groups also will be preferred.

Preferred photoresists of the invention typically comprise a resincomponent and a photoactive component. Preferably the resin hasfunctional groups that impart alkaline aqueous developability to theresist composition. For example, preferred are resin binders thatcomprise polar functional groups such as hydroxyl or carboxylate.Preferably a resin component is used in a resist composition in anamount sufficient to render the resist developable with an aqueousalkaline solution.

For imaging at wavelengths greater than 200 nm, such as 248 nm, phenolicresins are typically preferred. Preferred phenolic resins are poly(vinylphenols) which may be formed by block polymerization, emulsionpolymerization or solution polymerization of the corresponding monomersin the presence of a catalyst. Vinylphenols useful for the production ofpolyvinyl phenol resins may be prepared, for example, by hydrolysis ofcommercially available coumarin or substituted coumarin, followed bydecarboxylation of the resulting hydroxy cinnamic acids. Usefulvinylphenols may also be prepared by dehydration of the correspondinghydroxy alkyl phenols or by decarboxylation of hydroxy cinnamic acidsresulting from the reaction of substituted or nonsubstitutedhydroxybenzaldehydes with malonic acid. Preferred polyvinylphenol resinsprepared from such vinylphenols have a molecular weight range of fromabout 2,000 to about 60,000 daltons.

Also preferred for imaging at wavelengths greater than 200 nm, such as248 nm are chemically amplified photoresists that comprise in admixturea photoactive component and a resin component that comprises a copolymercontaining both phenolic and non-phenolic units. For example, onepreferred group of such copolymers has acid labile groups substantially,essentially or completely only on non-phenolic units of the copolymer,particularly alkylacrylate photoacid-labile groups, i.e. aphenolic-alkyl acrylate copolymer. One especially preferred copolymerbinder has repeating units x and y of the following formula:

wherein the hydroxyl group be present at either the ortho, meta or parapositions throughout the copolymer, and R′ is substituted orunsubstituted alkyl having 1 to about 18 carbon atoms, more typically 1to about 6 to 8 carbon atoms. Tert-butyl is a generally preferred R′group. An R′ group may be optionally substituted by e.g. one or morehalogen (particularly F, Cl or Br), C₁₋₈ alkoxy, C₂₋₈ alkenyl, etc. Theunits x and y may be regularly alternating in the copolymer, or may berandomly interspersed through the polymer. Such copolymers can bereadily formed. For example, for resins of the above formula, vinylphenols and a substituted or unsubstituted alkyl acrylate such ast-butylacrylate and the like may be condensed under free radicalconditions as known in the art. The substituted ester moiety, i.e.R′—O—C(═O)—, moiety of the acrylate units serves as the acid labilegroups of the resin and will undergo photoacid induced cleavage uponexposure of a coating layer of a photoresist containing the resin.Preferably the copolymer will have a M_(w) of from about 8,000 to about50,000, more preferably about 15,000 to about 30,000 with a molecularweight distribution of about 3 or less, more preferably a molecularweight distribution of about 2 or less. Non-phenolic resins, e.g. acopolymer of an alkyl acrylate such as t-butylacrylate ort-butylmethacrylate and a vinyl alicyclic such as a vinyl norbornanyl orvinyl cyclohexanol compound, also may be used as a resin binder incompositions of the invention. Such copolymers also may be prepared bysuch free radical polymerization or other known procedures and suitablywill have a M_(w) of from about 8,000 to about 50,000, and a molecularweight distribution of about 3 or less.

Other preferred resins that have acid-labile deblocking groups for usein a positive-acting chemically-amplified photoresist of the inventionhave been disclosed in European Patent Application 0829766A2 of theShipley Company (resins with acetal and ketal resins) and EuropeanPatent Application EP0783136A2 of the Shipley Company (terpolymers andother copolymers including units of 1) styrene; 2) hydroxystyrene; and3) acid labile groups, particularly alkyl acrylate acid labile groupssuch as t-butylacrylate or t-butylmethacrylate). In general, resinshaving a variety of acid labile groups will be suitable, such as acidsensitive esters, carbonates, ethers, imides, etc. The photoacid labilegroups will more typically be pendant from a polymer backbone, althoughresins that have acid labile groups that are integral to the polymerbackbone also may be employed.

As discussed above, for imaging at sub-200 nm wavelengths such as 193nm, preferably a photoresist is employed that contains one or morepolymers that are substantially, essentially or completely free ofphenyl or other aromatic groups. For example, for sub-200 nm imaging,preferred photoresist polymers contain less than about 5 mole percentaromatic groups, more preferably less than about 1 or 2 mole percentaromatic groups, more preferably less than about 0.1, 0.02, 0.04 and0.08 mole percent aromatic groups and still more preferably less thanabout 0.01 mole percent aromatic groups. Particularly preferred polymersare completely free of aromatic groups. Aromatic groups can be highlyabsorbing of sub-200 nm radiation and thus are undesirable for polymersused in photoresists imaged with such short wavelength radiation.

Suitable polymers that are substantially or completely free of aromaticgroups and may be formulated with a PAG of the invention to provide aphotoresist for sub-200 nm imaging are disclosed in European applicationEP930542A1 and U.S. Pat. Nos. 6,692,888 and 6,680,159, all of theShipley Company.

Suitable polymers that are substantially or completely free of aromaticgroups suitably contain acrylate units such as photoacid-labile acrylateunits as may be provided by polymerization of methyladamanatylacrylate,methyladamantylmethacrylate, ethylfenchylacrylate,ethylfenchylmethacrylate, and the like; fused non-aromatic alicyclicgroups such as may be provided by polymerization of a norbornenecompound or other alicyclic compound having an endocyclic carbon-carbondouble bond; an anhydride such as may be provided by polymerization ofmaleic anhydride and/or itaconic anhydride; and the like.

Preferred negative-acting compositions of the invention comprise one ormore materials (such as a crosslinker component e.g. an amine-basedmaterials such as a melamine resin) that will cure, crosslink or hardenupon exposure to acid, and a photoactive component of the invention.Particularly preferred negative acting compositions comprise a resinbinder such as a phenolic resin, a crosslinker component and aphotoactive component of the invention. Such compositions and the usethereof has been disclosed in European Patent Applications 0164248 and0232972 and in U.S. Pat. No. 5,128,232 to Thackeray et al. Preferredphenolic resins for use as the resin binder component include novolaksand poly(vinylphenol)s such as those discussed above. Preferredcrosslinkers include amine-based materials, including melamine,glycolurils, benzoguanamine-based materials and urea-based materials.Melamine-formaldehyde resins are generally most preferred. Suchcrosslinkers are commercially available, e.g. the melamine resins soldby Cytec under the trade names Cymel 300, 301 and 303. Glycoluril resinsare sold by Cytec under trade names Cymel 1170, 1171, 1172, urea-basedresins are sold under the trade names of Beetle 60, 65 and 80, andbenzoguanamine resins are sold under the trade names Cymel 1123 and1125.

For imaging at sub-200 nm wavelengths such as 193 nm, preferrednegative-acting photoresists are disclosed in WO 03077029 to the ShipleyCompany.

Photoresists of the invention also may contain other materials. Forexample, other optional additives include actinic and contrast dyes,anti-striation agents, plasticizers, speed enhancers, sensitizers (e.g.for use of a PAG of the invention at longer wavelengths such as I-line(i.e. 365 nm) or G-line wavelengths), etc. Such optional additivestypically will be present in minor concentration in a photoresistcomposition except for fillers and dyes which may be present inrelatively large concentrations such as, e.g., in amounts of from 5 to30 percent by weight of the total weight of a resist's dry components.

A preferred optional additive of resists of the invention is an addedbase, e.g. a caprolactam, which can enhance resolution of a developedresist relief image. The added base is suitably used in relatively smallamounts, e.g. about 1 to 10 percent by weight relative to the PAG, moretypically 1 to about 5 weight percent. Other suitable basic additivesinclude ammonium sulfonate salts such as piperidinium p-toluenesulfonateand dicyclohexylammonium p-toluenesulfonate; alkyl amines such astripropylamine and dodecylamine; aryl amines such as diphenylamine,triphenylamine, aminophenol,2-(4-aminophenyl)-2-(4-hydroxyphenyl)propane, etc.

The resin component of resists of the invention is typically used in anamount sufficient to render an exposed coating layer of the resistdevelopable such as with an aqueous alkaline solution. Moreparticularly, a resin binder will suitably comprise 50 to about 90weight percent of total solids of the resist. The photoactive componentshould be present in an amount sufficient to enable generation of alatent image in a coating layer of the resist. More specifically, thephotoactive component will suitably be present in an amount of fromabout 1 to 40 weight percent of total solids of a resist. Typically,lesser amounts of the photoactive component will be suitable forchemically amplified resists.

The resist compositions of the invention also comprise a photoacidgenerator (i.e. “PAG”) that is suitably employed in an amount sufficientto generate a latent image in a coating layer of the resist uponexposure to activating radiation. Preferred PAGs for imaging at 193 nmand 248 nm imaging include imidosulfonates such as compounds of thefollowing formula:

wherein R is camphor, adamantane, alkyl (e.g. C₁₋₁₂ alkyl) andperfluoroalkyl such as perfluoro(C₁₋₁₂alkyl), particularlyperfluorooctanesulfonate, perfluorononanesulfonate and the like. Aspecifically preferred PAG isN-[(perfluorooctanesulfonyl)oxy]-5-norbornene-2,3-dicarboximide.

Sulfonate compounds are also suitable PAGs, particularly sulfonatesalts. Two suitable agents for 193 nm and 248 nm imaging are thefollowing PAGS 1 and 2:

Such sulfonate compounds can be prepared as disclosed in European PatentApplication 96118111.2 (publication number 0783136), which details thesynthesis of above PAG 1.

Also suitable are the above two iodonium compounds complexed with anionsother than the above-depicted camphorsulfonate groups. In particular,preferred anions include those of the formula RSO₃— where R isadamantane, alkyl (e.g. C₁₋₁₂ alkyl) and perfluoroalkyl such asperfluoro (C₁₋₁₂alkyl), particularly perfluorooctanesulfonate,perfluorobutanesulfonate and the like.

Other known PAGS also may be employed in photoresists used in accordancewith the invention. Particularly for 193 nm imaging, generally preferredare PAGS that do not contain aromatic groups, such as theabove-mentioned imidosulfonates, in order to provide enhancedtransparency.

Photoresists of the invention also may contain other optional materials.For example, other optional additives include anti-striation agents,plasticizers, speed enhancers, etc. Such optional additives typicallywill be present in minor concentrations in a photoresist compositionexcept for fillers and dyes which may be present in relatively largeconcentrations, e.g., in amounts of from about 5 to 30 percent by weightof the total weight of a resist's dry components.

The photoresists used in accordance with the invention are generallyprepared following known procedures. For example, a resist of theinvention can be prepared as a coating composition by dissolving thecomponents of the photoresist in a suitable solvent such as, e.g., aglycol ether such as 2-methoxyethyl ether (diglyme), ethylene glycolmonomethyl ether, propylene glycol monomethyl ether; propylene glycolmonomethyl ether acetate; lactates such as ethyl lactate or methyllactate, with ethyl lactate being preferred; propionates, particularlymethyl propionate, ethyl propionate and ethyl ethoxy propionate; aCellosolve ester such as methyl Cellosolve acetate; an aromatichydrocarbon such toluene or xylene; or a ketone such as methylethylketone, cyclohexanone and 2-heptanone. Typically the solids content ofthe photoresist varies between 5 and 35 percent by weight of the totalweight of the photoresist composition. Blends of such solvents also aresuitable.

Liquid photoresist compositions may be applied to a substrate such as byspinning, dipping, roller coating or other conventional coatingtechnique. When spin coating, the solids content of the coating solutioncan be adjusted to provide a desired film thickness based upon thespecific spinning equipment utilized, the viscosity of the solution, thespeed of the spinner and the amount of time allowed for spinning.

Photoresist compositions used in accordance with the invention aresuitably applied to substrates conventionally used in processesinvolving coating with photoresists. For example, the composition may beapplied over silicon wafers or silicon wafers coated with silicondioxide for the production of microprocessors and other integratedcircuit components. Aluminum-aluminum oxide, gallium arsenide, ceramic,quartz, copper, glass substrates and the like are also suitablyemployed. Photoresists also may be suitably applied over anantireflective layer, particularly an organic antireflective layer.

Following coating of the photoresist onto a surface, it may be dried byheating to remove the solvent until preferably the photoresist coatingis tack free.

The photoresist layer (with overcoated barrier composition layer, ifpresent) in then exposed in an immersion lithography system, i.e. wherethe space between the exposure tool (particularly the projection lens)and the photoresist coated substrate is occupied by an immersion fluid,such as water or water mixed with one or more additives such as cesiumsulfate which can provide a fluid of enhanced refractive index.Preferably the immersion fluid (e.g., water) has been treated to avoidbubbles, e.g. water can be degassed to avoid nanobubbles.

References herein to “immersion exposing” or other similar termindicates that exposure is conducted with such a fluid layer (e.g. wateror water with additives) interposed between an exposure tool and thecoated photoresist composition layer.

The photoresist composition layer is then suitably patterned exposed toactivating radiation with the exposure energy typically ranging fromabout 1 to 100 mJ/cm², dependent upon the exposure tool and thecomponents of the photoresist composition. References herein to exposinga photoresist composition to radiation that is activating for thephotoresist indicates that the radiation is capable of forming a latentimage in the photoresist such as by causing a reaction of thephotoactive component (e.g. producing photoacid from the photoacidgenerator compound).

As discussed above, photoresist compositions are preferablyphotoactivated by a short exposure wavelength, particularly a sub-400nm, sub-300 and sub-200 nm exposure wavelength, with I-line (365 nm),248 nm and 193 nm being particularly preferred exposure wavelengths aswell as EUV and 157 nm.

Following exposure, the film layer of the composition is preferablybaked at temperatures ranging from about 70° C. to about 160° C.Thereafter, the film is developed, preferably by treatment with anaqueous based developer such as quaternary ammonium hydroxide solutionssuch as a tetra-alkyl ammonium hydroxide solution; various aminesolutions preferably a 0.26 N tetramethylammonium hydroxide, such asethyl amine, n-propyl amine, diethyl amine, di-n-propyl amine, triethylamine, or methyldiethyl amine; alcohol amines such as diethanol amine ortriethanol amine; cyclic amines such as pyrrole, pyridine, etc. Ingeneral, development is in accordance with procedures recognized in theart.

Following development of the photoresist coating over the substrate, thedeveloped substrate may be selectively processed on those areas bared ofresist, for example by chemically etching or plating substrate areasbared of resist in accordance with procedures known in the art. For themanufacture of microelectronic substrates, e.g., the manufacture ofsilicon dioxide wafers, suitable etchants include a gas etchant; e.g. ahalogen plasma etchant such as a chlorine or fluorine-based etchant sucha Cl₂ or CF₄/CHF₃ etchant applied as a plasma stream. After suchprocessing, resist may be removed from the processed substrate usingknown stripping procedures.

The following non-limiting examples are illustrative of the invention.All documents mentioned herein are incorporated by reference herein intheir entirety.

EXAMPLE 1 Di-block copolymer synthesis:Poly(2-(((trifluoromethyl)sulfonyl)amino)ethyl2-methylacrylate-block-2,3,3-trimethyl butyl acrylate)

The title block copolymer having the following structure was prepared asdescribed below:

A. Monomer solution 1: 30 weight percent (CH₃)CH═CH₂(C=O)O(CH₂)₂NHSO₂CF₃in anhydrous tetrahydrofuranB. Monomer solution 2: 30 weight percent CH₂═CH₂(C═O)O(CH)(CH₃)₂C(CH₃)₃in anhydrous tetrahydrofuranC. Initiator Solution: 1M of 1-octylperoxy-9-borafluoene in anhydrousTHF

A 100 ml flask with a magnetic stir bar is heated under vacuum to removeresidual moisture and then sealed under dry nitrogen. Add to the sealedflask 23.3 g (26.8 mM) of Monomer solution 1 and place the flask in abath at 20° C. Transfer 6 ml of Initiator solution to the flask and stirthe mixture in the flask for 5 hours. Then add 15.2 g (26.8 mM) ofMonomer solution 2 to the flask and continue stirring for another 5hours followed by quenching of the reaction with acidic methanol.

The reaction solution is then transferred to a round bottom flask andmost the tetrahydrofuran is removed at elevated temperature undervacuum. The concentrated polymer solution is then poured into a beakerof deionized water to precipitate the polymer. The polymer is then driedunder vacuum at 50° C. overnight.

EXAMPLE 2 Additional Block Copolymer Preparation

By procedures similar to those of Example 1, the following blockcopolymers are prepared:

EXAMPLE 3 Photoresist Preparation and Processing

A photoresist composition is prepared by admixing the followingmaterials in the specified amounts:

1. Resin component: Terpolymer of (2-methyl-2-adamantylmethacrylate/beta-hydroxy-gamma-butyrolactonemethacrylate/cyano-norbornyl methacrylate in an amount of 6.79 weight %based on total weight of the photoresist composition;2. Photoacid generator compound: T-butyl phenyl tetramethylene sulfoniumperfluorobutanesulfonate in an amount of 0.284 weight % based on totalweight of the photoresist composition;3. Base additive: N-Alkyl Caprolactam in an amount of 0.017 weight %based on total weight of the photoresist composition;4. Surfactant: R08 (fluorine-containing surfactant, available fromDainippon Ink & Chemicals, Inc.) in an amount of 0.0071 weight % basedon total weight of the photoresist composition5. Block copolymer: Polymer of Example 1 prepared as described inExample 1 above and in an amount of 0.213 weight % based on total weightof the photoresist composition.6. Solvent component: propylene glycol monomethyl ether acetate toprovide about a 90 percent fluid composition.

This photoresist composition containing is spin-coated onto siliconwafers, dried on vacuum hotplate to remove soft-plate and then exposedin an immersion lithography process with aqueous immersion fluiddirectly contacting the dried photoresist layers. In that immersionsystem, the photoresist layers is exposed to patterned 193 nm radiationat a dose of 24.1 mJ/cm² for the control photoresist layers and 23.4mJ/cm².

The photoresist layers is then post-exposed baked (such as at about 120°C.) and developed with 0.26N alkaline aqueous developer solution.

To evaluate leaching of resist components after the post-exposure bakeand before development, the immersion fluid is evaluated for thephotoacid in the resist and its photo-degradation byproducts by LC/massspectroscopy (60 second leaching time tested).

1. A method for processing a photoresist composition, comprising: (a)applying on a substrate a photoresist composition comprising: (i) one ormore resins, (ii) a photoactive component, and (iii) one or more blockcopolymers that are distinct from the one or more resins; and (b)immersion exposing the photoresist layer to radiation activating for thephotoresist composition.
 2. The method of claim 1 wherein the one ormore block copolymers are substantially non-mixable with the one or moreresins.
 3. The method of claim 1 or 2 wherein one or more of the blockcopolymers comprise (1) a developer affinity block and (2) a hydrophobicblock.
 4. The method of any one of claims 1 or 3 wherein one or more ofthe block copolymers comprise at least three distinct blocks or domains.5. The method of any one of claims 1 through 4 wherein the one or moreblock copolymers comprise hetero-substituted multi-ring carbocyclic arylgroups, sulfonamide and/or carboxy groups.
 6. The method of any one ofclaims 1 through 5 wherein the one or more block copolymers comprise onemore fluorine groups or fluorine-substituted groups.
 7. The method ofany one of claims 1 through 6 wherein the one or more block copolymerscomprise aqueous base-solubilizing groups and/or one or morephotoacid-labile groups.
 8. A coated substrate system comprising: asubstrate having thereon: a coating layer of a photoresist composition,the photoresist composition comprising: (i) one or more resins, (ii) aphotoactive component, and (iii) one or more block copolymers that aredistinct from the one or more resins.
 9. The system of claim 8 whereinan immersion lithography fluid contacts the top surface of thephotoresist coating layer
 10. The system of claim 8 or 9 furthercomprising an immersion photolithography exposure tool.
 11. The systemof any one of claims 8 through 10 wherein one or more of the blockcopolymers comprise (1) a developer affinity block and (2) a hydrophobicblock.
 12. A photoresist composition comprising: (i) one or more resins,(ii) a photoactive component, and (iii) one or more one or more blockcopolymers that are distinct from the one or more resins.
 13. Thephotoresist composition of claim 12 herein the one or more blockcopolymers are substantially non-mixable with the one or more resins.